# Is "Mg"_2"O"_2" the correct formula for magnesium oxide?

When writing the formula for an ionic compound, such as $\text{MgO}$, you reduce the subscripts to the lowest whole number ratio. So, you reduce $\text{Mg"_cancel ("2")"O"_cancel ("2")}$, to $\text{MgO}$. Both formulas indicate a 1:1 ratio of Mg to O in the compound.